Computer



May 17, 1949. M. 1 GREENOUGH 2,470,303

COMPUTER Filed Maron 5o, 19214 fyi.

SYNQ/ VULTASE Z/xl To maan? w55 Y /l /7 zo Puff/wdr T l5 22 am rasmf 5E Cod/W51? r Z6 if -f 300W INVENTOR. 'Mau-Z. empgylz www Patented May 17, 1.949

COMPUTER Maurice L. Greenough, Princeton, N. J., assigner .to Radio Corporation yof America, a corporation of Delaware AApplication March30, 1944, Serial No. 528,718

14 Claims.

ll This vinvention relates `tocomputers which `are operated to performa mathematical calculation in response to vtrains ofelectrical impulses representative ofthe:numbersinvolved in suchlcalculation. It has'for'ts principal object the provision ofanimproved computer `and methodof operation'whereby `diierent types of calculations maylbe:efiectedmoreisimply and with less apparatus "than lthat heretofore 'required for this purpose.

yThere have been provided in the past, various types of kcomputers whichfoperate in response rito trains of electrical pulses-representative of the num-bers involved in la 'calculation' to producea train of Velectrical pulses :representative of the result fof'the calculation. 'Many of these computers have been'fbased-onfthe binary numerical system in ordertoiminimizethe required number of electron dischargetubes and@ have involved the use of multivibrator units so operated that each unit represents'a diierent digital iposition ofthe number and thefdigit forthat position determines which electron .discharge'element ofthe unit `is conducting current. Such a r`computer leaves something to-be desired linthe way of simplicity for the reason that it`requires'two electron fdischarge elements for each digital'position ofthe numbers involved inthe calculation. `In some casesgthere is also involved the additional-dimculty of converting thecalculated data `from the binary systemv to 'fthe vdecimal fsystem.

`In accordance with the present invention, these difficulties are avoided by the provision of a gastriode saw tooth'oscillation generator which is operated from one stable operating condition to another in response'to pulses'of the pulse trains representative ofthe numbers involved in the calculation. vAs such a generator passes from one stable operating condition to another, its output voltage'varies in discretevsteps each of which may represent a different digit of the decimal system.

Important objects of the invention are' the provision of an improvedcomputer and methodvof operation whereby vvoltage pulses are translated into a voltage which lchanges by a discrete step in response' to each of such pulses; and the provision of an improved computer which maybe operated readilyto'perform calculations in any preferred numerical system.

The f invention "will be better understood from the vfollowing Idescription considered in connection with 'the accompanying drawings and lits scope I.is indicated bythe Yappended claims.

IR-'e'ferring Lto 'the drawings: Y.

. sistor R1.

Figure 1 is an explanatory diagram indicating therelation between the grid bias and plate current starting voltages of a saw tooth oscillation generator including a gas tube,

Figure `2 is a wiring diagram of a saw tooth oscillation generator having the output voltage characteristic illustrated by Fig. 1,

Figure 3 is a Wiring diagram of a single computer unit which, for example, may form one decade o1" a complete computer, and

Figure 4 is a Wiring diagram of a coupling circuit which is adapted to be connected between units similar to that of Fig. '3 for triggering the following decade once each time the count of the preceding decade is completed.

Fig. i. shows the relation between grid bias potential and .the voltage at which current starts through the plate or anode circuit of a gas triode such as the RCA 884. It will be noted that increasing the negative bias increases the plate voltage at which the gas triode takes current and vice versa. With the exception of a fixed component, the voltage required to start plate current is a constant times the grid bias voltage. If such a gas tube is connected to operate asa saw tooth oscillation generator, as illustrated by Fig. 2, the peak amplitude of the generated saw tooth wave increases in direct proportion to the grid bias potential.

The saw tooth oscillation generator of Fig. 2 includes a gas triode tube Ill which has its grid bias potentialapplied from an adjustable source shown as a battery Il and its plate or anode potential applied from Va terminal -i-B through a re- Connected between the cathode and anode of the tube IU is a capacitor C1 which is provided with output terminals i2. In the operation of the generator of Fig. 2, the capacitor G1 is charged from the terminal |B through the resistor R1 and is discharged through the tube I0 when thefcapacitor voltage has attained a value dependent on the grid potential of the tube l0. After each discharge of the capacitor, the voltage lagain rises, resulting in a saw tooth wave, at the terminals l2.

As previously indicated, the peak amplitude of the generated saW tooth pulse vor wave increases indirect proportion to the grid bias potential of the tube lll. If this grid bias potential is derived from and is directly proportional to the saw tooth output pulse amplitude, the saw tooth oscillation generator maintains any established operating condition for the reason that the generated grid bias potential at any saw tooth pulse amplitude -is just that required to sustain oscillations at that amplitude. How this principle of operation is utilized to produce a voltage which changes by discrete steps is readily understood in connection with the computer unit of Fig. 3.

The computer unit of Fig. 3 includes a peak detector or rectifier I which is coupled to the capacitor C1 through a capacitor I3 and resistor i4 and functions to charge a capacitor C connected in parallel with a circuit including a resistor I6 and an indicator Il which may be a micro-ammeter or other instrument suitable for indicating the voltage of the capacitor C. Bias potential is applied from the resistor I through a terminal I8 and the secondary winding of a transformer I9 to the grid of the tube I0. Input pulses are applied 4to the terminal 2li, output pulses are delivered at a terminal 2|. A synchronization voltage of frequency f is applied to the grid of the tube I0 through the transformer I9.

With a synchronizing voltage of frequency f thus applied to the grid of the tube 10, oscillations can be generated only at a frequency f, i etc.

Saw tooth pulse amplitude at a frequency of will be twice that at a frequency of f because the build-up or capacitor charging time is twice as long. Similarly saw tooth pulse amplitude at a frequency of is three times that at a frequency of f etc. Since the frequency of oscillation can have only certain discrete values, such as f r, r, f r

so can the voltage e@ across the capacitor C have only certain distinct values which are separated by equal discrete steps. Whenever established at some arbitrary value, the frequency and grid bias potential will always swing to the nearest of these allowable or stabilized values. By establishing successive values of grid bias potentials there are established successive conditions of stable equilibrium.

This mode of operation follows from the fact that the grid bias voltage of the tube I0 is the resultant of (1) the unidirectional voltage of the battery I I which is constant, (2) the synchronizing voltage applied through the transformer I9 which has a constant frequency and amplitude, and (3) the voltage drop of the upper part of the resistor I6 which is 'unidirectional and has a value dependent on the output voltage of the oscillator. Since the oscillator has a constant amplitude output voltage for any given bias potential of the tube I0, it is apparent that the charge of the capacitor C, the voltage drop of the resistor I6 and the potential of the output lead 2| will be maintained constant so long as no pulses are applied to the input leady 20.

It will be noted that the unidirectional voltage of the battery I I is opposed to the unidirectional voltage drop across the upper part of the resistor IB so that the grid bias potential of the tube I0 becomes more positive as the voltage drop across the resistor I6 increases.

:As pointed out above, the oscillator can operate only at the frequency of the synchronizing volt--y age applied through the transformer I9 or at some submultiple of that frequency. This is so because the oscillator is locked in step with the synchronizing frequency and must therefore operate at this or a submultiple frequency.

If the oscillator is operating at the synchronizing frequency, for example, the application of a negative pulse to the input lead 20 makes the grid of the tube I0 more positive so that the operating frequency of the oscillator is reduced by one half and the oscillator output voltage is increased by one discrete step. This voltage increase is somewhat larger than the input pulse Voltage required to push the oscillator into its new stable operating condition. The nal charge of the capacitor C, the final grid bias voltage of the tube I0 and the final voltage of the output lead 2| are therefore independent of the voltage of the input pulse and are altogether dependent on the output voltage of the oscillator.

The next pulse applied to the input lead func- .tions in the same Way to temporarily unlock the oscillator from the synchronizing frequency so that the operating frequency of the oscillator is reduced by the same amount as by the rst input pulse. Under these conditions, the voltage of the output lead 2l is changed by one discrete step as previously explained and is maintained at this new value until a subsequent input pulse is applied.

Thus, to operate the unit of Fig. 3 as a computer, it is necessary to apply through the terminal 20 pulses of sufficient energy to push the unit into successive conditions of stable operation. As

. these pulses are applied one after another, the

voltage of the capacitor C is changed by discrete steps until it attains a value at which a pulse is delivered through the coupling circuit of Fig. 4 to a following unit or decade which is similar to that of Fig. 3.

The coupling or trigger circuit of Fig. 4 includes a gas triode 22 which has its cathode connected to the ungrounded terminal 2I of the capacitor C of Fig. 3, has its grid biased to a potential determined by a battery 23 and functions to charge a capacitor 24 when its cathode is driven suiiciently negative by the potential of the capacitor C. When this occurs, there is transmitted through a coupling capacitor 25 and resistor 26 to the next unit a pulse whereby a count of one is registered in this decade. The capacitor. 24 is discharged through its parallel-connected resistor while a potential representative of a count of ten (in the case of a decade) is being built up on the prceeding unit.

The unit of Fig. 3 has been operated quite Satisfactorily to accumulate a count of ten input pulses. A greater number of pulses may be accumulated if a higher plate supply voltage is provided. The best results have been obtained by starting with ec equal to zero and applying negative pulses through the lead 20 to raise the Voltage of the capacitor C for adding the applied pulses. Pulses of positive polarity are applied to the lead 20 to lower the voltage of the capacitor C for substracting the applied pulses. The in"- stantaneous net number of pulses must, of course, be greater than zero.

The computer unit of Fig. 3 has the advantage of simplicity. A gas triode and a diode are all the tubes required to add and subtract up to ten. Only one additional gas triode is required for discharging the capacitor C and triggering the following unit or decade. The required amplitude of the triggering or input pulse is not critical but mayvar-y betweenlimits of 1:50% for the reason 'that-it frounds off to the nearest whole number. Only a total of iifteen tubes are required to count .to-one million, Thisis. an economy of apparatus not.heretofore realized in connection with other ftypesof electronic computers.

I` claim as my invention:

1. yThe combination of an oscillation generator .includinga storage device, impedance means for controllingvthe rate at which current is stored in -saiddevice and a gaseous electron discharge device-.provided with an anode circuit arranged to discharge said storage device and with a grid circuit .arranged to control the potential at which said discharge is initiated, and means connected .between vsaid storage device and said grid for applying to said grid a bias potential which is stabirlizedat successive Ypredetermined values dependent on lthe charge of said storage device.

2. The combination oi" an oscillation generatorvincluding a storage device, impedance means vfor controlling the rate at which current is stored in said device and a gaseous electron discharge device .provided with an anode circuit arranged to discharge said storage device and with a grid circuit arranged to control the potential at which said discharge is initiated, means connected between said storage device and said grid for apply- Ving to said grid a bias. potential which is stabilized at vsuccessive predetermined values dependent on the charge-ofA said storage device, and means for controlling said values so that they are all difierent from one another and are separated by discretesteps.

`3. The combination of an oscillation generator including a storage device, impedance means for controlling the rate at which current is stored in said device and a gaseous electron discharge device provided with an anode circuit arranged to discharge said storage device and with a grid circuit arranged to control the potential at which said dischargeis initiated, parallel connected resistance and capacitance means, means for detectingthe output potential of said generator and `applying said detected potential to said parallel connected means, and means for applying a component of said detected potential to said grid.

4, The combination of an oscillation generator including Va storage device, impedance means for controlling the rate at which current is stored in said device and a gaseouselectron discharge device provided with an anode circuit arranged to discharge said storage device and with a grid circuit arranged to control the potential at which said ldischarge is initiated, parallel connected resistance and capacitance means, means for detecting the output potential of said generator and applying said detected potential to said parallel connected means, means for applying a component of said detected potential to said grid, and means for superimposing a synchronizing potentialon said detected potential component.

5. The combination of an oscillation generator including a storage device, impedance means for controlling the rate at which current is stored in said device and a gaseous electron discharge device provided with an anode circuit arranged to discharge said storage device and with a grid circuit arranged to control the potential at which said discharge is initiated, parallel connected resistance and capacitance means, means for detecting the output potential of said generator and applying said detected potential to said parallel connected means, means for applying a component of said detected potential to said grid, means for superimposing .a synchronizing potential on said detected potential component, and meansfor -superimposing on said detected potential control saiddischarge is initiated, parallel connected resistance and capacitance means, means for detecting the output potential of said generator and applying said detected potential to said parallel connected means, means for applying a component of said detected potentialto said grid, means for superimposing a synchronizing potential on said detected potential component, means for superimposing on said detected potential control pulses for changing said generator output voltage by discrete steps, and means responsive to a predetermined value of said detected potential for transmitting a pulse to a utilization device.

7. The combination of a plurality of units each including a saw tooth generator oi the type wherein a gaseous conduction electron discharge device has a storage device connected in its output circuit and functions to discharge said storage device in response to the application of a predetermined potential to its input circuit, means for detecting the output potential of said generator, parallel-connected capacitance and resistance means through which a component of said detected potential is utilized to control the input potential of said generator and means for superimposing a synchronizing potential on said component, means for applying to a rst of said units control pulses whereby the potential of its parallel-connected capacitance and resistance means is changed by discrete steps, and means connected between the parallel-connected capacitance and resistance means of said rst unit and those of a second of said units ior increasing the generator output potential of said second unit by one discrete step in response to a predetermined potential of the parallel-connected capacitance and resistance means of said ilrst unit.

8. The combination or an oscillation generator of the type wherein a gaseous conduction electron discharge device has a storage device connected in its output circuitand functions to discharge said storage device in response to the application of a'predetermined potential to its control grid, means for applying to said grid a bias potential proportional in value to the output voltage of said generator, means for applying to said grid a constant frequency alternating potential whereby the operating frequency of said generator may be stabilized at successive values differing from one another by a predetermined amount, and means for applying to said grid successive voltage pulses whereby said operating irequency ispushed from one to another of said successive values.

9. The combination of an oscillation generator of the type wherein a gaseous conduction electron discharge device has a storage device connected in its output circuit and functions to discharge said storage device in response to the application of a predetermined potential to its control grid, means for applying to said grid a bias potential proportional in value to the output voltage oi said generator, means for applyarmste ir'ig to sa'id grid a constant frequency alternating potential whereby the operating frequency of said generator may be stabilized at successive values differing from one another by a predetermined amount, and means for applying to said grid successive positive pulses whereby said operating frequency is pushed to successive values each lower than the preceding value by said predetermined amount.

10. The combination of an oscillation generator of the type wherein a gaseous conduction electron discharge device has a storage device connected in its output circuit and functions to discharge said storage device in response to the application of a predetermined potential to its control grid, means for applying to said grid a bias potential proportional in value to the output voltage of said generator, means for applying to said grid a constant frequency alternating potential whereby the operating frequency of said generator may be stabilized at successive values differing from one another by a predetermined amount, means for applying to said grid succesysive voltage pulses whereby said operating frequency is pushed from one to another of said successive values, and means for applying to said grid successive negative pulses whereby said operating frequency is pushed to successive values each higher than the preceding value by said predetermined amount.

11. The combination of an oscillation generator of the type wherein a gaseous conduction electron discharge device has a storage device connected in its output circuit and functions to discharge said storage device in response to the application of a predetermined potential to its control grid, means for applying to said grid a bias potential proportional in value to the output voltage of said generator, means for applying to said grid a constant frequency alternating potential whereby the operating frequency of said generator may be stabilized at successive values differing from one another by a predetermined amount, means for applying to said grid successive voltage pulses whereby said operating frequency is pushed from one to another of said successive values, and means for producing an output pulse in response to a predetermined number of changes in said operating frequency.

12. The combination of an oscillation generator of the type wherein a gaseous conduction electron discharge device has a storage device connected in its output circuit and functions to discharge said storage device in response to the application of a predetermined potential to its control grid, means including a detector and a capacitor and resistor each connected across said detector for applying to said grid a bias potential proportional in value to the output voltage of said generator, means for applying to said grid a constant frequency alternating potential whereby the operating frequency of said generator may be stabilized at successive values differing from one another by a predetermined amount, and means including said resistor for applying to said grid successive voltage pulses whereby" said operating frequency is pushed from one to another of said successive values.

13. The combination of an oscillation generator of the type wherein a gaseous conduction electron discharge device has a storage device connected in its output circuit and functions t0 discharge said storage device in response to the application of a predetermined potential to its control grid, means including a detector anda 'capacitor and resistor each connected across said detector for applying to said grid a bias potential proportional in value to the output voltage of said generator, means for applying to said grid a constant frequency alternating potential whereby the operating frequency of said generator may be stabilized at successive values differing from one another by a predetermined amount, means including said resistor for applying to said grid successive voltage pulses whereby said operating frequency is pushed from one to another of said successive values, and means connected across said capacitor for producing an output pulse in response to a predetermined number of said changes in said operating frequency.

'14. The combination of an oscillation genera-` tor of the type wherein a gaseous conduction electron discharge device has a storage device connected in its output circuit and functions to discharge said storage device in response to the application of a predetermined potential to its control grid, means including a detector and a capacitor and resistor each connected across said detector for applying to said grid a bias potential proportional in value to the output voltage of said generator, means for applying to said grid a constant frequency alternating potential whereby the operating frequency of said generator may be stabilized at successive values differing from one another by a predetermined amount, means including said resistor for applying to said grid successive voltage pulses whereby said operating frequency is pushed from one to another of said suc cessive values, a second electron discharge device having its input circuit connected across said capacitor, and means including a second capacitor yconnected in the output circuit of said second electron discharge device for producing an output pulse in response to a predetermined number of said changes in said operating frequency.

MAURICE L. GREENOUGH.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Name Date Fitz Gerald Mar. 1, 1938 OTHER REFERENCES Number 

